This invention relates to a direction-changeable structure of the hand tool handles and particularly to a hand tool of multi-function and large range of working torque.
In the prior art of hand tools there are versatile designs. Some for single function, the other for multi-function; some for small torque transmission, the other for large torque transmission, etc. The ultimate aim of those is to provide the users with an efficient, powerful and convenient way to have their works done. However, those hand tools which can support large torque without damaging themselves have only single function, and those having multi-function can hardly support large torque and are damaged easily when greater torque is applied.
Referring to FIGS. 5 and 6 these are two conventional hand tools. Both have disadvantages. The hand tool shown on FIG. 6 is more stable in use and would not shake but because it is operated only by thumb and index finger, it can not transmit great torque. The hand tool shown on FIG. 5 is a general one with separate parts. Although it can transmit larger torque than the former can, it is not stable and it shakes in use for the movement of hand is not continuous, and the hand itself must turn back in order to continue rotating the hand tool constantly. Thus, this type of hand tool handle is not suitable for more precise working. Obviously, for works of greater torque and higher concentricity, such as tapping and slightly reaming, the handles mentioned above can not meet the requirements. Particularly, for work that needs high precision at the beginning and great torque later, the handle still needs to be improved.
It is, therefore, the object of the present invention to obviate those drawbacks and to provide a handle of hand tool with multi-function and large range of working torque.